The operation of a gas turbine with liquid fuels, for example oil, requires, at regular intervals, water flushing of the fuel lines in order that oil residues remaining in the fuel lines cannot combust or coke and thus lead to damage and disruption to operation. According to the internal prior art known to the applicant, gas turbines are typically supplied with flush water under pressure via a flush water line, such that the pressurized flush water can remove, for cleaning, the fuel present in the fuel lines. This amounts to displacement flushing, wherein the displaced fuel can be returned, with parts of the flush water, into a fuel supply container that supplies the gas turbine. If this return takes place over an unsuitably long time, in particular during shutdown of the gas turbine, the compressor end pressure of the gas turbine can become so low that the displacement flushing must be halted in order to prevent undesired penetration of fuel and/or flush water from the fuel lines into the burner and thus into the combustion chamber of the gas turbine.
To that end, the flushing procedure known from the prior art provides limiting the flushing duration, in particular during shutdown of the gas turbine, in order to avoid such drawbacks. In this context, flushing durations of less than 30 seconds are generally selected in order to be able to ensure reliable operation.
However, a time limitation of this type has the drawback that the flushing of the fuel lines by means of the flush water is not sufficiently complete, and thus in turn undesirably large quantities of liquid fuel can remain in the fuel lines. This gives rise to the technical requirement of proposing a gas turbine which permits better flushing of the fuel lines. Also to be proposed is a method which avoids the drawbacks known from the prior art and permits improved and more efficient flushing of the fuel lines of the gas turbine. This is to take place in particular during shutdown of the gas turbine.